Core apparatus for forming arched pipe



March 22, 1960 T. D. M GINNIS ETAL Filed March 26, 1957 CORE APPARATUSFOR FORMING ARCHED PIPE 4 Sheets-Sheet l JEF- "uu 1 v /33 29 5 3/ 3OTHO/V4.5" 0. M6/NNI$ 774200025 1M MOHLE WALL/4M E. lV/CHGLS INVENTORS giga March 22, 1960 T. D. M GINNIS ETAL CORE APPARATUS FOR FORMING ARCHEDPIPE Filed March 26, 1957 4 Sheets-Sheet 2 7 77104449 0. M5 GIN/V15THEODORE W. MOI/LE- WILL mu E. N t/104s INVENTORS ATTORNEY! March'zz,1960 T. D.YMOGINNIS ETAL 2,929,125

CORE APPARATUS FOR FORMING ARCHED PIPE Filed March 26, 1957 4Sheets-Sheet 3 7710/1445 0. M 6 llV/V/S THEOO OQE W. MOI-ILE W/L 4 /4 ME, NICHOLS IN V EN TORS ATTORNEYS March 22, 1960 T. D. MGGINNIS ETALCORE APPARATUS FOR FORMING ARCHED PIPE Filed March 26, 1957 4Sheets-Sheet 4- o w 7 X77 7 ATTOR/VV J length than has CORE APPARATUSFOR FORNHNG' ARCHED PIPE Thomas D. McGinnis, Theodore W. Mollie, andWilliam E. Nichols, Houston, Tex., assignors to Turtle Back PipeCompany, Houston, Tex., a corporation of Texas Application March 26,1957, Serial."- N 648,694

14 Claims.- (Cl. 25-128):

This invention relates to an improved apparatus for forming arched pipeof concrete or other hardenable plastic material. This application is acontinuation-in- Part of our co-pending application, Serial Number541,918, filed October 21, 1955, and now abandoned.

One rather conventional procedure for forming round peripheral lengtheffective to define the diameter of the opening through the pipe.

When the concrete is poured into the space between the mold members fromtoo great a height, there is a tendency for the aggregate to settle tothe bottom and thus seriously weaken the pipe. As a result, bothbuilding codes as well as the industry itself have .placed limitationsupon this amount of free drop such that pipe formed by this method isnecessarily in rather short sections. Also, when concrete is poured intoupstanding mold members in this manner, it is impossible to observe thereinforcement and make sure that it is not shifted or jarred out ofplace.

Arched pipe is preferred over round pipe inasmuch.

as, for example, it requires less head room and less backfill. However,in order to take optimum advantage of the structural characteristics ofthe arch, the side -of the opening through the pipe opposite the archshould define the maximum lateral dimension of such opening. That is,the arched portion of the pipe should not be permitted to curl backunder at its lower side.

As in the ease of round pipe, it is necessary in the forming of archedpipe to collapse the inner mold member prior to removing same. However,with the side opposite the arch defining the maximum lateral dimensionof the mold member, it was found difficult to re move the inner moldmember according to earlier techniques without injury to either the moldmember or the formed pipe. That is, the mere reduction of the peripherallength of the curved portion of the mold member did not permit itscollapse into a shape for removal.

It is an object of this invention to provide a mold for forming archedpipe of this type in sections of greater heretofore beenpossihle and,more particularly, in a manner which permits observance of thereinforcement during pouring of the concrete or other hardenable plasticmaterial. p

Another object is to provide an inner mold member for use in theformation of such pipe which is easilyand readily. collapsible forremoval from the opening through the formed pipe without damage toeither the mold member or the pipe.

Still another object isflto provide a novel operator 2,92%,125 PatentedMar. 22;, 1960 for selectively, expanding and collapsing an inner moldmember of the character described in the foregoing object. a

A still more particular object is to provide such an inner mold memberwith means for facilitating the lifting thereof.

Yet a further object is to providepallets so constructed as to beparticularly well suited for forming arched pipe of concrete or the likein accordance with the present invention.

Other objects, advantages and features of this invention will beapparent to one skilled in the art upon a consideration of the writtenspecification, the attached claims and the annexed drawings.

In the drawings, wherein like reference characters are used throughoutto designate like parts:

Fig. l is a perspective view of one form of mold constructed inaccordance with this invention and including an inner mold memberdisposed in an expanded position within an outer mold member to define aspace therebetween which is closed at opposite ends by pallets and intowhich concrete or the like may be poured in mold "ta-ken along 22 ofFig- 1, and resting upon afhorizontal Fig. 3 is a perspective view ofthe inner mold 'member of Figs. 1 and 2 moved to a collapsed positionwithin an arched pipe formed thereby, and with the outer mold member andpallets removed from the pipe for purposes of illustration;

Fig. 4 is another perspective view of the collapsed inner mold member ofFig. 3, but removed from the opening throughv the pipe;

Fig. 5 is an enlarged sectional view of the double hinge construction atone corner of the inner mold member of Figs. .1 to 4;

Fig. 6 is a perspective view of formed pipe shown in Fig. 3; v

Fig. 7 is an end view of another form of inner mold member constructedin accordance with this invention and disposed in expanded positionwithin a formed pipe from which the outer mold member and pallets haveFig. 9 is a perspective view of the collapsed, inner mold member of Fig.8 removed from the formed pipe;

Fig. 10 is an end elevational' view of still another form of mold whichis similar to, but an improvement upon,

the form of Figs. land 2; and

Fig. 11 is a longitudinal section view of the mold of Fig. 10, takensubstantially along broken line 11--11 of Fig. 10.

According to the present invention, there is provided an apparatus forforming arched pipe of the type described wherein an inner mold member,expandable into a substantially rigid shape having a contourcorresponding to the openingthrough the pipe, is supported in itsexpanded position substantially horizontally above a similarly disposedouter mold member to define a space therebetween corresponding tothethickness of the arch of the pipe. With the mold members so disposed,the space is filled and the flat side of the inner mold member iscovered with concrete or the like to form the side opposite its concavepc the spigot end of the rtion which permits 11:va'j

tion of the reinforcement above the fiat side of the inner mold memberfor the entire length of such mold mem bers. As a result, movement ofthe reinforcement during pouring of the material may be corrected. I

The inner mold member is supported in properly spaced relation to theouter mold member by means of pallets or end mold members through whichthe inner mold member is received. These pallets are releasablyattachable to opposite open ends of the outer mold member and receivethe inner mold member in such a manner as to tightly close the oppositeends of the space between the inner and outer mold members, and arefurther of such construction as to resist displacement of the inner moldmember due to buoyancy of the concrete during filling of said space.

Further in accordance with this invention, the side of the expandedinner mold member which defines the maximum lateral dimension of theopening through the pipe is formed by a pair of flat sections which areabuttable with one another along their inner longitudinal edges andhingedly connected about their outer longitudinal edges to a curvedportion of the mold member which defines the arch of the pipe. Thecurved portion includes means for reducing the lateral length thereofeffective to define said arch, so that the inner longitudinal edges ofthe fiat sections may be moved out of abutment and the outerlongitudinal edges thereof moved inwardly relative to one another so asto reduce the width of the side effective to define the maximum lateraldimension of the mold member and thereby collapse the mold member topermit its removal from the opening through the pipe.

The lateral length of the curved portion of the inner mold membereffective to define the arch of the pipe is reduced upon the collapse ofa plurality of relatively movable sections which make up such portion.In accordance with a preferred form of inner mold member, these sectionsof the curved portion include a central curved section and a sidesection hingedly connected to each longitudinal edge of the centralsection and substantially perpendicularly to the flat sections. Thus,the width of the side effective to define the maximum lateral dimensionof the mold member and the lateral length of the curved portioneffective to define the arch of the pipe are reduced upon inwardswinging of the side sections.

This preferred form of inner mold member is provided with a novelactuator for selectively expanding and collapsing same, which actuatorcomprises a toggle linkage connecting a fiat section with the centralcurved section. The inner mold member is also provided with internallateral bracing which supports a crank shaft for 1 the toggle linkage aswell as tnbular parts at each end of said mold member adapted to receivea fork lift.

According to another form, the curved portion includes "a pair ofsections in abutment with one another along their inner longitudinaledges, such that upon movement of the inner longitudinal edge of one ofthe fiat sections and one of the sections of the, curved portion out ofabutment with and inwardly with respect to the other section of each, aswell as movement of the hingedly connected outer longitudinal edges ofeach inwardly toward one another, a similar collapsing effect as in thepreferred form is accomplished to permit the removal of the mold member.3

Referring now to the drawings, and particularly the preferred form ofmold shown in Figs. 1 to 5, an outer mold member 20 having asubstantially concave curved portion and open at its side opposite thecurved portion may be provided with legs-21 or other means forsupporting it in a substantially horizontal position, as shown in Fig.2. A pair of pallets or end mold members 22 and 23 arereleasablyfattached in any suitable manner to the opposite open ends ofouter mold member 20 and mold member in properly spaced relation abovethe outer mold member 20. These pallets include flat and curved sectionsadapted to close opposite ends of such space and shaped to provide theformed pipe A with a bell end 24 (Fig. 3) and a spigot end 25 (Figs. 3and 6), respectively.

The preferred form of inner mold member, designated in its entirety bythe reference character 26, is shown in Figs. 1 and 2 in expandedposition and received closely within the openings through pallets 22 and23, and in Figs. 3 and 4 in a collapsed position to permit its removalfrom the opening through the formed pipe. As can be seen from thedrawings, this inner mold member includes a curved portion 27 whichdefines the arch of the pipe to be formed, and a side 28 opposite thecurved portion which defines the maximum lateral dimension of the moldmember. vThe side 28 is formed by a pair of fiat sections 29 and 30which are connected in abutment with one another along their innerlongitudinal edges by hinge 31. These sections are made of asubstantially rigid and inflexible material, such as 7 inch sheet steel,or otherwise braced by lateral ribs to prevent fiexure under the weightand pressure of the concrete.

For the purpose of permitting its lateral length efiective to define thearch of the pipe to be reduced, the curved portion 27 is made up of acentral curved section 32 and side sections 33, such sections also beingconstructed to withstand the pressure of the concrete. The side sectionsare hingedly connected at 34 to the outer longitudinal edges of each ofthe fiat sections 29 and 30 substantially perpendicularly to said fiatsections, and also along their opposite edges to the longitudinal edgesof central section 32 by means of hinges 35, such that the connectedflanges of the two hinges form the section 33.

The hinges 34 and 35 are shown in more detail in Fig. 5, wherein it maybe seen that as the side sections 33 are swung inwardly(counterclockwise) about hinge 3S and hinge 31 moves downwardly, thewidth of flat sections 29 and 30 which defines the maximum lateraldimension of the mold member as well as the lateral length of curvedportion 27 of the mold member etfective to define the arch of the pipewill be reduced, whereby the entire mold member is collapsed to theposition shown in Figs. 3 and 4 to permit its removal from the openingthrough the pipe.

It should be noted with respect to the inner mold member 26 that theflat sections 29 and 30 are abuttablc with one another in alignedrelation so that the side 28 of the mold member is also fiat. Althoughthis is preferred from a structural standpoint, it is not essential. Itshould also be noted that the entire lateral length of curved portion 27of the mold member need not define the curvature of the arch but rather,as indicated on a small scale by side sections 33, some of such portionmay define a flat surface connecting the curavture defining the archwith the side 28 of the mold member. In this manner, the height of thepipe may be increased to any desired degree as long, of course, as thesections 29 and 30 are abuttable with one another to define the maximumlateral dimension of the mold member. In this same connection, it willbe still further understood that the side sections 33 are hingedlyconnected to the fiat sections 29 and 30 substantially perpendicularlythereto to permit them to swing inwardly about hinges 35 in the mannerabove-described.

With the inner mold member 26 expanded, and preferably held in expandedposition by a plurality of vertical braces 36 spaced longitudinallythereof, it is disposed in a substantially horizontal position spacedabove the similarly disposed outer mold member 20 in a manner previouslydescribed, so as to define an arched space37 therebetween which isclosed at opposite ends by end mold members 22 and 23. As indicated in'Fig. 1, reinforcing rods 37a may be placed in predetermined spacedrelation within space 37 as well as above the side 28 of the inner moldmember for a purpose "well known in the art.

In accordance with the present invention, the concrete or otherhardenable plastic material is poured in its plastic state into thespace 37 and onto the side 28 of the inner mold member so as to surroundsame and form the pipe while the mold members are/disposed in theabove-described substantially horizontal position. Obviously, thematerial will fill the space and cover the side 28 of the inner moldmember above a level corresponding to the upper edge of outer moldmember 20 so that it may be troweled off to form a substantially smoothside on the pipe A, as shown in Figs. 3 and 6. Not only does this methodof filling the forms reduce to a minimum the free drop of .the material,but also it permits observance at substantially the entire period ofsuch pouring of the spacing and placement of the reinforcing rods 37a.

When the material has hardened so as to form the pipe A which is shownin Figs. 3 and 6, the inner mold member 26 may be collapsed, in a mannerpreviously. mentioned, to permit to be moved freely longitudinally ofthe opening through the pipe. Obviously, such removal is accomplishedwithout damage to either the mold member or the formed pipe since it isnecessary to force neither. That is, the-inner mold member is readilycollapsed for removal and use in the forming of another pipe of thedesired configuration. Although in Fig. 3, the outer end end moldmembers have apparently been removed prior to removal of the inner moldmember, it should be understood that this is merely to better illustratethe formed pipe since it is the practice to remove the outer and endmold members subsequent to removal of the inner member.

The form of inner mold member shown in Figs. 7 to 9 and designated inits entirety by reference character 33 is shown in an expanded positionwithin the opening through a just-formed pipe A in Fig. 7 and in acollapsed position in Figs. 8 and 9, the outer mold member being removedfor the same reason as in Fig. 3. It will be understood, of course, thatthe arched pipe A may be formed in a manner described in connection withFigs. 1 to 5 with the use of an outer and end mold members similar tothose shown in Figs. 1 and 2.

As in the case of inner mold member 26 of Figs. 1 to 5, inner moldmember 38 is expandable into a shape hav ing a curved portion 39defining the arch of the pipe and a side 40 opposite the curved portionwhich defines the maximum lateral dimension of the mold member. Theopposite side 4% is formed by a pair of substantially inflexible flatsections 41 and 42 each of which is abuttable with the other along itsinner longitudinal edgeand hingedly connected at 43 about its outerlongitudinal edge with the curved portion 39. However, in contrast tothe flat sections 29 and 30 of inner mold member 26, the abutting innerlongitudinal edges of flat sections 41 and 42 are tapered in thedirection of movement of one of said fiat sections with respect to theother fiat section between abutting and non-abutting positions. Thus, ascan be seen from Fig. 8, the tapered inner longitudinal edge of fiatsection 41 is tapered inwardly and downwardly to permit it to be movedin a similar direction over the opposite edge of section 42 from theposition of Fig. 7 to that of Fig. 8.

The curved portion 39 of inner mold member 38 includes a pair of curvedsections 44 and 45 having inner longitudinal edges tapered for abutment,as shown in Fig. 7 As in the case of fiat sections 41 and 42,'theabutting edges of sections 44 and 45 are tapered in the direction ofmovement of one of said sections into and out of abutment with the othersection. Thus, upon such movement of the inner longitudinal edge ofsection 44 over and'out of abutment with the correspondingly taperededge of section 45, the lateral length of curved portion 39 effective todefine the arch of the pipe is reduced to permit collapse of the innermold member.

'Each of the movable sections '41 and 44 is provided with a stop member46 adjacent its inner edge adapted, in the expanded position of the moldmember, to overlap the inner edge of the section with which it abuts.Not only does the part 46 serve as a means for aligning the edges ofabutting sections, but also serves as a water seal for the seam or jointextending longitudinally of the mol inem ber between the sections.

Each of the movable mold member sections 41 and 4-4 may be moved intoand out of abutting relation with its adjacent section 42 and 45,respectively, by an operator 47 operable from one end of the moldmember. Each such operator 47 may comprise a rotatable crank 48 carriedupon a support 49 attached to one of the mold member sections andextending longitudinally of the mold member to a point adjacent one endthereof for manual manipulation. Connecting thecrank and movable sectionis a link 51 and eccentric 50, the latter being rotatable with crank48'and the link pivotally connecting the movable section and eccentric,such that rotation of the crank in one direction will serve to urge themovable section to an abutting and expanded position, while movement inan opposite direction will urge it to a collapsed position out ofabutment with its adjacent section. Thus, as can be seen in Figs. 7 and8, rotation of the crank 48 in a clockwise direction urges section 41 toan expanded position with its edge in abutment with that of section 42,while rotation in a counterclockwise direction urges section 41 out ofabutment with section 42 for collapsing the side 40 of the mold member.Obviously, the opposite is true of the function of operator 47 forcurved section 44 of curved portion 39 of the mold member.

Although the form of mold illustrated in Figs. 10 and 11 corresponds inits more basic aspects to the form of Figs. 1 and 2, it is animprovement thereoverin a number of respects to which the description tofollow will be principally directed.

As in the earlier described form, the outer mold member 55 of the moldof Figs. 10 and 11 include-s a longitudinally extending portion 56 whichis curved to the outer periphery of the arch of the pipe to be formedand open along each end as well as opposite its curved length. Thecurved portion 56 is supported upon spaced lateral plates 57 which arein turn carried above longitudinal runners 58 so as to dispose the outermold member 55 with its open top uppermost, as shown in the drawings.

Each of the pallets or mold members 59 and 60 for the bell and spigotends of the pipe is made up of an arched portion 61 and a flat portion62 fixedly'secured to the arched portion for defining an opening63therethrough to receive the expanded inner mold member 64. When thepallets are attached to the outer mold member 55 in a manner to supportthe inner mold member in properly spaced relation above the outer moldmember, as will be described hereinafter, the flat portions 62 thereoffixedly secured to the arched portions 61 provide maximum resistance toraising of the inner mold member due to the buoyance of the concrete.

As can be seen from the drawings, the arched portions 61 of the palletsare formed oversize so that they may be attached across the open ends ofthe outer mold member 55 with their outer edges projectingconcentrically outwardly of the curved portion 56. Thus, with the inneredge of said arched portions 61 curved to define the inner periphery ofthe arch of the pipe so ,as to closely fit the expanded inner moldmember 64, the overlapping outer edges insure against leakage from thespace between the inner and outer mold members by compensating foroutof-round in the latter. 7

The means for releasablyv attaching a palletacross an open end of theouter mold comprises a plurality of brackets 65, some of which arebroken away in Fig. 10, spaced circumferentially about the end of thecurved 7 portioni56, of the outer mold member to form slots 66 forholding the outer edges of the arched portion of .each pallet. in .theoverlapping position above mentioned. Screws 67 are received in thebrackets for forcing the outer edge so held against the ends of thecurved portion 56 for closing'the ends of the space. More particularly,the ends of the screws 67 are received within recesses 68 in the outeredge of each pallet, at least two of which screw ends and recesses aretapered for aligning the pallets circumferentially of the brackets.

. .The inner mold member 64 is very similar to its counterpart 26in themold form of Figs. 1 and 2 in that it includes a longitudinallyextending curved portion 69 which definesthe arch'of the pipe to beformed, and a side 70 opposite the curved portion which defines themaximum lateral dimension of the mold member. Also, the side 70isformed; by apair of flat sections 71 and 72 connected at their innerlongitudinal edges by a hinge 73. .Stillfurther, the curved portion 69is made up of a central section 74 and side sections 75 hingedlyconnected along one edge at 76 to opposite longitudinal edges of thecentral section 74. The side sections 75 are hingedly connected alongtheir opposite edges at 77 to the outer longitudinal edges of fiatsections 71 and 72. Thus, when the inner mold member is expanded, asshown in Fig. 10, the side sections 75 will be disposed substantiallyperpendicular to flat sections 71 and 72, and the inner edges of saidfiat sections will be in abutment and aligned with one anotherso thattheside 70 is flat. As in t he case of the first described. form ofmold, the inner mold member 64 is adapted to be collapsed or expanded byreducing or extending the lateral length of curved portion 69 thereof.In this improved form of mold, such collapse or expansion isaccomplished by means of an operator '78 comprising a toggle linkage connecting a flat section, such as 72, with the central section 74 of thecurved portion 69 for selectively swinging them toward and away fromeach other. More particularly, one link 79 of the linkage is pivotallyconnected to a lateral flange 80 on the flat section 72, and the otherlink 81 is connected to a crank shaft 82 journaled within lateral braces83 on and spaced longitudinally of central curved section 74. As can beseen from Figs. 10 and 11, an arm 84 is provided on an outwardlyextending portion of the shaft so as to rotate the shaft in acounterclockwise direction (Fig. 10) for actuating the toggle linkage tocollapse the inner mold member.

More particularly, the shaft 82 extends through the entire length of theinner mold member for connection witha toggle linkage 78 at each endthereof so that the operator may be manipulated from either end.

A-pair of tubular members 85 are fixedly secured to two or more of theoutermost braces 83 for extension longitudinally inwardly of one end ofthe inner mold member a relatively short distance. These members 85 areof such an inner diameter and so spaced apart as to accommodate a forklift for lifting inner mold members of substantial weight. Thesecurement of the members 85 to two or more of the braces 83 distributesthe stress on the inner mold member when lifted.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the operation of the apparatus.

It-will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This iscontemplatedby and is Within the scope of theclaims. As. many possible embodiments may be made of the inventionwithout departing from the scope thereof, it is ,to be understood thatall matter herein set forth. or

.sgoiytfni'intlieaccomp'anying' drawings is to be interpretedasillu'strative and not in a limiting sense.

invention having been described, what is claimed 1. For use. inv theformation of arched pipe of con crete or other. hardenable plasticmaterial, an inner mold member expandable into a shape having alongitudinally extending curved..por'tion defining the inner peripheryof the. arch of the'pip'e and a. side opposite the curved portion whichdefines the maximum lateral dimension of the mold member, said oppositeside being formed by a pair of flat sections in abutment with oneanotheralong their inner. longitudinal edges and hingedly connected withthe curved portion about their outer longitudinal edges, and said curvedportion including means for reducing the lateral length thereofeffective to define the arch of the pipe, whereby the inner longitudinaledges of the fiat sections may be moved out of abutment and the outerlongitudinal edges thereof moved inwardly with respect to one another tocollapse the mold member and permit its removal from the formed pipe.

2. For use in the formation of arched pipe of concreteor otherhardenable plastic material, an inner mold member expandable into ashape having a longitudinally extending curved portion defining theinner periphery of the arch of the pipe and a side opposite the curvedportion which defines'the maximum lateral dimension of the mold member,said opposite side being formed by a pair of flat sections in abutmentwith one another along their inner longitudinal edges, and said curvedportion including, a side section hingedly connected to the outerlongitudinal edge of each of the flat sections of the opposite sidesubstantially perpendicularly thereto and a central curved'sectionhingedly connected to the side sections, whereby the lateral'length ofthe curved portion effective to define the arch of the pipe as well asthe width of the opposite side effective to define the maximum lateraldimension of the mold member are reduced upon swinging of the sidesections inwardly toward one another and movement of the innerlongitudinal edges of the hat sections out of abutment.

3. A mold of the character defined in claim 2, includingtoggle linkagepivotally connected at opposite ends to one of said fiat sections andsaid central curved section and operable for selectively expanding orcontracting said inner mold member.

4. An inner mold member of the character defined in claim 3, wherein thepivotal connection at one end of said toggle linkage includes a shaftextending through the length of the inner mold member, and handles areattached to each end of the shaft for operating the toggle linkage ateach end of the inner mold member.

5. For use in the formation of arched pipe of concrete or otherhardenable plastic material, an inner mold member expandable into ashape having a longitudinally extending curved portion defining theinner periphery of the arch of the pipe and a flat side which definesthe maximum lateral dimension of the mold member, said flat side beingformed by a pair of flat sections hingedly connected together with theirinner longitudinal edges in abutment with one another, and said curvedportion including, a side section hingedly connected to the outerlongitudinal edge of each of the flat side sections substantiallyperpendicularly thereto and a central curved section hingedlyconnected'to the side sections of the curved portion,.whereby thelateral length of the curved portion efiective to define the arch of thepipe as well as the width of the opposite side eifective to define themaximumlateral dimension of the mold member are reducedupon swinging of.the side jsections inwardly toward one another and the hingedlyconnected longitudinal edges of the flat sections downwardly and out ofabutment withjone another.

6. An inner mold member of the character defined in claim 5 sending aseries of flanges secured to the interior ofthe centralicurved sectiontransversely to the inner mold.member,' 'a-"longitudina'lly extendingcrank shaft journaledwithin said flanges, a toggle linkage connecting'said sh'aft'to one ofsaid flat sections, and

8. For use in the formation of arched pipe of con- I crete or otherhardenable plastic material, an inner mold member expandable into ashape having a longitudinally extending curved portion 'defining theinner periphery of the arch of the pipe and a side opposite the curvedportion which defines the maximum lateral dimension of the mold member,said opposite side being formed by a pair of flat sections in abutmentwith one another along their inner longitudinal edges and hingedlyconnected with the curved portion about their outer longitudinal edges,said curved portion also including a pair of sections in abutment withone another along their inner longitudinal edges, such that uponmovement of one of the sections of each of the opposite side and thecurved portion out of abutment with and inwardlywith respect to theother section, the lateral length of the curved portion effective todefine the arch of the pipe and width of the opposite side efiective todefine the maximum lateral dimension of the mold member are reduced tocollapse and permit removal of the mold member from the formed pipe.

9. An inner mold member of the character defined in claim 8, wherein theabutting inner longitudinal edge of the one section of each of theopposite side and curved portion movable inwardly of the other sectionthereof is tapered in the direction of such movement.

10. An inner mold of the character defined in claim 9, including anoperator having a crank operable from one end of the mold member formoving the movable section of each of the opposite side and curvedportion into and out of abutment with the other section thereof.

11. For use in the formation of arched pipe of concrete or otherhardenable plastic material, an inner mold member which includes, alongitudinally extending curved portion comprising a plurality ofrelatively movable sections expandable to define the inner periphery ofthe arch of the pipe and collapsible to reduce the lateral length of theportion efiective to define the arch, and a pair of flat sectionshingedly connected about their outer longitudinal edges to the sectionsof the curved portion for expansion therewith into abutment with oneanother along their inner longitudinal edges to define the maximumlateral dimension of the mold member, said inner longitudinal edgesofthe flat sections being movable out of abutment and the outerlongitudinal edges thereof being movable inwardly toward one anotherupon collapse of the curved portion sections to permit reduction of thewidth of the flat sections efiective to define the maximum lateraldimension of the mold member and removal of the mold member from the.formed pipe.

12. An inner mold of the character defined in claim 11, wherein therelatively movable sections of the curved portion include a centralcurved section, and a side section hingedly connected to eachlongitudinal edge of the curved section and substantiallyperpendicularly to the fiat sections, whereby the curved portion iscollapsible upon swinging of the side sections inwardly with respect toone another.

13. An innermold of the character defined in claim 11, wherein therelatively movable sections of the curved portion include a pair ofsections in abutment with one another along their inner longitudinaledges, such that upon movement of one of the flat sections and one ofthe sections of the curved portion out of abutment with and inwardlywith respect to the other section of each, the lateral length of thecurved portion etfective to define the arch of the pipe and width of theflat sections effective to define the maximum lateral dimension of the amold member are reduced to collapse and permit removal of the moldmember from the formed pipe.

14. An inner mold of the character defined in claim 12, wherein theabutting inner longitudinal edges of the flat sections are hingedlyconnected together for swinging movement out of abutment in response tosaid inward swinging of the side sections.

References Cited in the file of this patent UNITED STATES PATENTSChiverton May 29, 1956

